Indicating instrument

ABSTRACT

The invention relates to an indicating instrument, particularly for a motor vehicle, comprising an approximately circular scale ( 12 ) which is placed on a dial ( 5 ), provided for a physical quantity, and along which a pointer ( 10 ) can be displaced whereby being able to be rotatably driven about an axis of rotation. Additionally provided is a marking that indicates a particular area of the scale ( 12 ). The marking is placed on a part ( 27 ), which is situated underneath the plane of the dial ( 5 ) whereby enabling it to be rotatably driven about the axis or rotation of the pointer ( 10 ) into a control position. The dial ( 5 ) comprises, along the movement path of the marking a window ( 13 ) through which the marking can be viewed from the front of the indicating instrument.

[0001] The invention relates to an indicating instrument, particularly for a motor vehicle, comprising an approximately circular scale, arranged on a dial, for a physical quantity, along which a pointer that can be driven rotatably about an axis of rotation can be moved, and comprising a marking indicating a particular area of the scale, the marking being arranged on a component that is arranged below the plane of the dial such that it can be driven rotatably by a marking drive about the axis of rotation of the pointer into a control position, and in that the dial has along the movement path of the marking a window through which the marking is visible from the front side of the indicating instrument.

[0002] In the case of such indicating instruments, it is known to arrange along the scale a row having luminous elements for which the luminous element or elements respectively controlled forms/form the marking. In the event of a defect or failure of a luminous element, it is a complicated matter to exchange the luminous means of this luminous element. Furthermore, accurate marking is not possible, since the luminous elements have a specific minimum length, and thus an indication is possible only digitally in a fixed module width of the row of the luminous elements.

[0003] DE 197 37 679 A discloses an indicating instrument of the type mentioned at the beginning in the case of which the marking is an optical device by means of which light of a light source arranged behind the component carrying the marking is directed through the window.

[0004] In a further indicating instrument of the type mentioned at the beginning (EP-A-0 785 416), the component carrying the marking is an optical conductor into one end of which light of a light source is launched, and at whose other end the light is coupled out below the window.

[0005] EP-A-0 900 686 discloses an indicating instrument whose dial is enclosed in the same plane by an annular component that carries a marking of luminous design and can be driven rotatably by a marking drive. In this case, the annular component is partially covered by a fixed cover plate.

[0006] DE 198 01 298 A discloses an indicating instrument with a dial behind which there is arranged an optical conductor into which light can be launched from a light source and through which the dial can be transilluminated from the rear side.

[0007] It is an object of the invention to provide an indicating instrument of the type mentioned at the beginning that is constructed simply and in a fashion not susceptible to defects, and that permits the marking to be indicated in an at least largely analog fashion.

[0008] This object is achieved according to the invention by virtue of the fact that arranged between the dial and component carrying the marking is an optical conductor into which light can be launched by a light source and through which the light can be coupled out so that it can be applied to the component carrying the marking.

[0009] This design leads to a simple illumination of the dial. Since furthermore no permanently arranged elements are present, but a marking arranged on a component that can be driven rotatably, the said marking can be brought unalogously exactly into any desired control position along its movement path. The mechanical construction with simple components reduces the susceptibility of the indicating instrument to defects. Owing to the arrangement of the component carrying the marking below the plane of the dial, no parts project over this plane.

[0010] Likewise, for the purpose of illuminating the dial simply, it is possible to arrange between dial and component carrying the marking an optical conductor into which light can be launched by a light source, and by which light can be coupled out onto the rear side of the dial in a fashion illuminating the transilluminable scale and/or transilluminable numerals.

[0011] In order to configure the illumination, both of the dial and of the marking in a particularly simple way, it is possible to arrange that a single optical conductor can apply light to the transilluminable scale and/or to the transilluminable numerals, as well as to the component carrying the marking.

[0012] If that surface of the component carrying the marking to which light can be applied is designed as a light reflector, the illumination of the window in the dial is further amplified.

[0013] In order to reduce and simplify the components of the indicating instrument, the optical conductor can have a cylindrical lug that projects on the side of the optical conductor averted from the dial, is coaxial with the axis of rotation of the pointer, and forms a slide bearing for the toothed ring carrying the component carrying the marking.

[0014] The window can extend radially inside or radially outside the scale, or together with the scale in a fashion covering it.

[0015] Furthermore, the window can be a cutout in the dial.

[0016] If the window is formed by a transparent or translucent region of the dial, that region of the indicating instrument situated behind the dial is protected against soiling.

[0017] The marking can mark a specific value of the scale in a punctiform fashion. By punctiform it is to be understood that only a single indicated value is indicated by the marking. A marking can in this case be, for example, a point, a line marking or an arrow directed radially relative to the scale.

[0018] In a preferred design, the scale can be a driving speed scale, and the punctiform marking can be a setting marking of the set driving speed forming the control position of a traveling speed controller or a traveling speed limiter.

[0019] A further possibility consists in that the marking extends along a specific area of the scale, it being possible to design the marking like a scale or like a bar.

[0020] In this case, the scale-type or bar-like marking can be a warning area that can be set variably as a function of a further quantity.

[0021] This is the case, for example, when the scale is an engine speed scale and the warning area is an engine speed warning range for an internal combustion engine.

[0022] The component can in this case be driven rotatably into the control position as a function of the respective operating temperature of the internal combustion engine. It is thereby possible that at a low operating temperature, for example after the start of operation, the warning range indicating the maximum permissible speed is located in a low engine speed range of the scale, and moves into a higher engine speed range of the scale in accordance with the rise in operating temperature.

[0023] The component can be an arm that extends radially from the axis of rotation and carries the marking.

[0024] In order to obtain a uniform background in the window, the component is preferably a disk that is arranged centrally relative to the axis of rotation and carries the marking.

[0025] A simple design of the drive of the marking is achieved by virtue of the fact that the component carrying the marking is arranged at a toothed wheel or toothed ring that is supported rotatably in a central fashion relative to the axis of rotation and can be driven rotatably by a drive pinion of the marking drive.

[0026] If the marking drive is a stepping motor, not only is it possible to achieve a control position that can be exactly specified, but energization is necessary only to change the position of the marking, but not to retain the position of the marking, and this leads to a saving in energy.

[0027] Designs of the invention are illustrated in the drawing and are described in more detail below. In the drawing:

[0028]FIG. 1 shows a side view of an indicating instrument in section,

[0029]FIG. 2 shows a first exemplary embodiment of a plan view of the indicating instrument according to FIG. 1, and

[0030]FIG. 3 shows a second exemplary embodiment of a plan view of the indicating instrument according to FIG. 1.

[0031] The indicating instrument illustrated in FIG. 1 has an approximately pot-shaped carrier 1 that is fastened on a base plate. Arranged inside the pot of the carrier 1 is an optical conductor 3 that is in the shape of a circular disk and rests with the aid of an integral cylindrical lug 4 on the base of the carrier 1.

[0032] Situated on the side of the optical conductor 3 averted from the base of the carrier 1 is a dial 5 that projects radially with its edge region beyond the optical conductor 3 and rests on the end face of the circumferential pot wall 6 of the carrier 1.

[0033] The edge region of the dial 5 is pressed onto the end face of the pot wall 6 through a radially circulating clamping ring 7.

[0034] The dial 5, optical conductor 3, carrier 1 and base plate 2 centrally have a continuous cutout 8 through which a pointer shaft 9 penetrates. On the end of the side of the dial, the pointer shaft 9 supports a radially directed pointer 10 that, upon rotation of the pointer shaft 9, sweeps with its pointer tip 11 over a scale 12 that is arranged in the shape of a circle and whose scale marks can be transilluminated.

[0035] Approximately three-quarters of the circular scale is enclosed by a transparent region of the dial 5 that forms an arcuate window 13. In this arrangement, the optical conductor 3 reaches radially up to the inner boundary of the arcuate window 13, while the radially outer boundary of the window 13 is formed by the inner circumference of the clamping ring 7.

[0036] Serving the purpose of rotary drive for the pointer 10 is a pointer drive 14 that is fastened on the side of the base plate 2 averted from the carrier 1 and whose drive journal 15 is connected to the pointer shaft 9 coaxially in a rotationally secure fashion.

[0037] The cylindrical lug forms a slide bearing on which a toothed ring 16 is rotatably mounted with its radially circulating inner circumference. The toothed ring engages with its radially directed teeth 17 in the teeth of a drive pinion 18 whose axis of rotation extends parallel to the axis of rotation of the pointer shaft 9.

[0038] The drive shaft 19 of the drive pinion 18 projects through a cutout 23 into the base of the carrier 1 and is connected coaxially in a rotationally secure fashion to the drive journal 20 of a marking drive 21 that is arranged, projecting through a cutout 22 in the base plate 2, on the side of the base of the carrier 1 averted from the optical conductor 3. Arranged on the toothed ring 16 is an annular disk 27 that projects radially up to below the window 13, and whose surface facing the optical conductor 3 and the window 13 is designed as a light reflector.

[0039] Arranged in the base of the carrier 1 is, furthermore, a light source 24 by means of which there is launched axially into the optical conductor 3 in the region of the lug 4 light that is deflected at a deflecting surface 25 into the radially directed region 26 of the optical conductor 3 and is distributed there over the entire circulating radially directed region 26.

[0040] The scale marks of the dial 5 bordering one side of the optical conductor are transilluminated by light coupled out of the optical conductor 3.

[0041] The light coupled out on the surface of the optical conductor 3 opposite the dial 5 strikes the disk 27 carrying the marking as reflected light, and thus illuminates this marking. Since the disk 27 is designed as a light reflector 28, the arcuate window 13 is furthermore illuminated. The design of the indicating instrument illustrated in FIG. 1 is the same for both the exemplary embodiments illustrated in FIGS. 2 and 3.

[0042] In FIG. 1, the scale 12 is an engine speed scale on which the pointer 10 indicates the respective speed of an internal combustion engine of a motor vehicle.

[0043] Applied to the disk 27 in the region of the window 13 as a scale-type marking 29 is an engine speed warning range that is not to be exceeded so as to avoid damage to the internal combustion engine. Since the maximum permissible engine speed is a function of the respective engine temperature, the latter is detected by a temperature sensor (not illustrated) and the marking drive 21 is correspondingly controlled. The latter uses the drive pinion 18 and the toothed ring 16 to rotate the disk 27 into a control position in which the maximum mark of the scale-type marking 29 is opposite the position of the engine speed scale that corresponds to the maximum permissible engine speed corresponding to the instantaneous engine temperature. With rising engine temperature, the maximum permissible engine speed also rises, such that the position of the scale-type marking 29 is varied correspondingly.

[0044] In FIG. 2, the scale 12 is a traveling speed scale on which the pointer 10 indicates the respective traveling speed of a motor vehicle. Applied to the disk 27 in the region of the window 13 is a line marking 30 that serves as setting marking of a traveling speed controller. The marking drive 21 is controlled in accordance with the traveling speed that is desired by a driver of a motor vehicle and is to be controlled by a traveling speed controller. Said marking drive uses the drive pinion 18 and the toothed ring 16 to drive the disk 27 into a control position in which the line marking 30 is opposite the position of the driving speed scale that corresponds to the traveling speed set. 

1. An indicating instrument, particularly for a motor vehicle, comprising an approximately circular scale, arranged on a dial, for a physical quantity, along which a pointer that can be driven rotatably about an axis of rotation can be moved, and comprising a marking indicating a particular area of the scale, the marking being arranged on a component that is arranged below the plane of the dial such that it can be driven rotatably by a marking drive about the axis of rotation of the pointer into a control position, and the dial having along the movement path of the marking a window through which the marking is visible from the front side of the indicating instrument, characterized in that, arranged between the dial (5) and component carrying the marking is an optical conductor (3) into which light can be launched by a light source (24) and through which the light can be coupled out so that it can be applied to the component carrying the marking.
 2. The indicating instrument as claimed in claim 1, characterized in that arranged between the dial (5) and component carrying the marking is an optical conductor (3) into which light can be launched by a light source (24), and by which light can be coupled out onto the rear side of the dial (5) in a fashion illuminating the transilluminable scale (12) and/or transilluminable numerals.
 3. The indicating instrument as claimed in claim 2, indicating instrument as claimed in claims 16 and 17, characterized in that a single optical conductor (3) can apply light to the transilluminable scale (12) and/or to the transilluminable numerals, as well as to the component carrying the marking.
 4. The indicating instrument as claimed in one of the preceding claims, characterized in that that surface of the component carrying the marking to which light can be applied is designed as a light reflector (28).
 5. The indicating instrument as claimed in one of the preceding claims, characterized in that the optical conductor (3) has a cylindrical lug (4) that projects on the side of the optical conductor averted from the dial (5), is coaxial with the axis of rotation of the pointer, and forms a slide bearing for the toothed ring (16) carrying the component carrying the marking.
 6. The indicating instrument as claimed in one of the preceding claims, characterized in that the window extends radially inside or radially outside the scale (12), or together with the scale (12) in a fashion covering it.
 7. The indicating instrument as claimed in one of the preceding claims, characterized in that the window is a cutout in the dial.
 8. The indicating instrument as claimed in one of claims 1 to 4, characterized in that the window (13) is formed by a transparent or translucent region of the dial (5).
 9. The indicating instrument as claimed in one of the preceding claims, characterized in that the marking marks a specific value of the scale (12) in a punctiform fashion.
 10. The indicating instrument as claimed in claim 9, characterized in that the scale (12) is a driving speed scale, and the punctiform marking is a setting marking of the set driving speed forming the control position of a traveling speed controller or a traveling speed limiter.
 11. The indicating instrument as claimed in one of claims 1 to 7, characterized in that the marking extends along a specific area of the scale (12).
 12. The indicating instrument as claimed in claim 11, characterized in that the marking (29) is designed like a scale or a bar.
 13. The indicating instrument as claimed in claim 12, characterized in that the scale-type or bar-like marking (29) is a warning area.
 14. The indicating instrument as claimed in claim 13, characterized in that the scale (12) is an engine-speed scale, and the warning area is an engine speed warning range for an internal combustion engine.
 15. The indicating instrument as claimed in claim 14, characterized in that the component can be driven rotatably into the control position as a function of the respective operating temperature of the internal combustion engine.
 16. The indicating instrument as claimed in one of the preceding claims, characterized in that the component is an arm that extends radially from the axis of rotation and carries the marking.
 17. The indicating instrument as claimed in one of claims 1 to 15, characterized in that the component is a disk (27) that is arranged centrally relative to the axis of rotation and carries the marking.
 18. The indicating instrument as claimed in one of the preceding claims, characterized in that the component carrying the marking is arranged at a toothed wheel or toothed ring (16) that is supported rotatably in a central fashion relative to the axis of rotation and can be driven rotatably by a drive pinion (18) of the marking drive (21).
 19. The indicating instrument as claimed in one of the preceding claims, characterized in that the marking drive (21) is a stepping motor. 